Family M80


Summary Holotypes Alignment Tree Genomes Literature

Summary for family M80

Family type peptidaseM80.001 - Wss1 peptidase (Saccharomyces cerevisiae), MEROPS Accession MER0069292 (peptidase unit: 23-223)
Content of familyPeptidase family M80 includes isopeptidases.
History Identifier created: MEROPS 9.3 (7 September 2010)
Targeting of proteins for subcellular localization and degradation can involve tagging the target protein with ubiquitin, SUMO or NEDD8 proteins, and several peptidase families are involved in removing these protein tags. The protein tag forms an isopeptide bond between its C-terminal glycine and the epsilon amino group of a lysine side chain on the target protein. The Wss1 metallopeptidase from Saccharomyces cerevisiae releases SUMO from conjugates by cleaving the isopeptide bond (Mullen et al., 2010). Wss1 stands for 'weak suppressor of Smt3' because the gene acts as a suppressor of a mutation in the SMT3 gene, which encodes the yeast homologue of SUMO (van Heusden & Steensma, 2008). Other desumoylating peptidases exist in family C48.
Catalytic typeMetallo
Active site residuesH115 E116 H119 H125 
Active siteThe metal-binding ligands are thought to be the histidines within the motif His-Glu-Xaa-Xaa-His-(Xaa)6-His motif, and the glutamate is thought to be a catalytic residue. The metal is assumed to be zinc.
Activities and specificitiesWss1 (M80.001) was shown in vitro to release SUMO from poly-SUMO-conjugates, but not to release ubiquitin from poly-ubiquitin conjugates. However, Wss1 could release an N-terminal ubiquitin from a poly-SUMO chain (Mullen et al., 2010).
Molecular structurePeptidases in family M80 are usually multi-domain proteins; in the case of Wss1 (M80.001) in addition to the peptidase domain (known as a WLM domain) there are two C-terminal ubiquitin-binding domains known as 'little finger' domains (Mullen et al., 2010). Family M80 is included in clan MA subclan M (the Met-zincins) because of the presence of the conserved HEXXHXXGXXH motif.
Basis of clan assignmentPredicted active site residues for members of this family and thermolysin, the type example for clan MA, occur in the motif HEXXH
Distribution of family Bacteria -  
Archaea -  
Protozoa details  
Fungi details  
Plants details  
Animals -  
Viruses -  
Biological functionsThe Wss1 isopeptidase is found in the nucleus near the nuclear membrane, and in dividing cells is exclusive to the mother cell (van Heusden & Steensma, 2008).
ReviewsHickey et al., 2012
Statistics for family M80Sequences:337
Identifiers with PDB entries:0
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
Wss1 peptidaseM80.001-
F14J16.17 protein (Arabidopsis thaliana)M80.A01-
At1g80210 protein (Arabidopsis thaliana)M80.A02-
wss1 g.p. (Schizosaccharomyces pombe)M80.A03-
SPCC1442.07c g.p. (Schizosaccharomyces pombe)M80.A04-
family M80 non-peptidase homologuesnon-peptidase homologue-
family M80 unassigned peptidasesunassigned-